Picking up Dirty Minds: How Our Brains ­Influence Love, Sex, and Relationships, an overview of developments in "the neuroscience of love" by journalist and science writer Kayt Sukel, jogged a fond memory. Part of my early initiation as the lone male-mascot editor at ELLE, it turned out, took place at a story meeting in which the subject of ­libido came up. I offered that I saw it more or less as just one of the ­primal appetites, like hunger—not much more ­complicated, given a certain passage of time, than "Shall we hit the rib joint tonight, darling, or go Thai?"

Er...no? I was gently given to understand, to the accompaniment of a few sighs and giggles, that the maintenance of the habit of intimacy was, in the eyes of my colleagues, a good deal more complicated than that. Emotional mind-set, relationship psychology, the barometric pressure of the domestic atmo­sphere, maybe the hormonal readings on a ­given day, and perhaps less effable elements besides—all ­entered into what could never be reduced to any kind of ­simple Newtonian equation. Ah, said I, with a dawning ­recognition of familiar, if seemingly impenetrable, complications. It's all so much more...conditional than the average fellow would have it be. I lean away from theories about how men and women are different in essential, hardwired ways, but now and then, there's really nothing else to say but vive la différence.

In Dirty Minds, it was the ­cotton-top ­tamarin ­monkeys that did it for me. I distrust the reverse anthro­pomorphism that animal experiments ­easily ­lead us into. But really, how perfect is this: We know that cuddling and mating release the neuro­transmitter oxytocin in a whole range of mammal­ian brains, ­including ours, and that this chemical ­cascade in turn ­fosters pair-­bonding. A 2010 study of ­tamarin couples looked ­further into this phenomenon and, Sukel reports, established that ­"snuggling and grooming were behind the [oxytocin] variance in females, while for men it came down to how much sex they were having." In the ­tamarin duos that showed high oxy­tocin ­levels, "males initiated the cuddling their mate ­wanted, and females solicited the sex their mate was after." Go ahead, call me reductive, but this ­passage put me right back in that story meeting.

Sukel's book fairly bristles with such causes to ­reflect on our erotic complexity, via data from ­animal and ­human experiments, genetics and epige­netics, endocrinology, and neuroimaging. But ­Chapter 12, "My Adven­tures with the O-Team," is the high point of the whole enterprise: The ­author consented to have herself strapped into an fMRI machine in a Jason-esque mesh mask to render her head immobile and to bring herself to orgasm while her brain was being scanned by the clanking ­machine enveloping her. After the short shudder of one ­demure climax that she thought did the trick came the request from the tech guy: Uh, fail ­better? So she rose womanfully to the challenge and ­really rode one home. Tech guy: "It was ­really, really great." Her reward? A 16-slice scan, reproduced in the book, of her brain on orgasm, lit up like a freaking Christmas tree. Serving the advancement of ­science can't get much better than that.